Steam heating system



Dec. 5, 1950 A. F. HUBBARD 2,532,550

STEAM HEATING SYSTEM Filed May 21, 1948 2 Sheets-Sheet 1 F IIlllllllllllllllIlllllllllllllllllllllllllllll||Illlllllllllll!!!llllllllllllllIllllllllll L g8 26 34 IIIIQIIE FIG. a;

IN VEN TOR. ARTHUR E HUBBARD FIG; 5.

ATTORNEY Dec. 5, 1950 A, F, HUBBARD 2,532,550

STEAM HEATING SYSTEM Filed May 21, 1948 2 Sheets-Sheet 2 I N VEN TOR. ARTHUR E HUBBARD ATTORNEY fiatenteci 15cc.

UNITED STATES PA EN OFFICE Arthur F. Hubbard, Moline, 111., assignor to The Herman Nelson Corporation, Moline,- lll., acorporationof Illinois ApplicationMay 21 1948, Serial No. 28,322

( Cl; 2 37r-e9 Glaims. 1

The present invention is related generally to vapor heat transfer systems and more particularly to steam heating systems. The principal object 501 ,my invention relates to the provision of a novel and improved steam heating system in which the temperature distribution in theheati'ng elements is more uniform than has beenheretofore z-commercially attained. Another object relates to the provision otia heating system which operates withouthoise clue to water hammer or to air gurgling through. the condensate.

A steam heatingsystem-of this type now known in the-artis provided with athermostatically-operated condensate .return trap connectedbetween the exhaust header and the return .line. trap valve is closed responsive to the heat of the steam passing through and opens responsive to the cooling action .of the accumulated condensate. When the main supply valve isopen, steam condenses .in the heating elementat a rapid .rate, flooding thelower portion of the element before the condensate is sufiiciently cooled to cause the trap to open and drain off the condensate. This results in uneven heating of the element and also unequal expansion and contraction of the heat.- ing tubes, and the intermittent flooding causes disturbing noises.

When the steam supply-is throttled, condone sation of the steam in the element results in. a

substantial pressure drop across the throttle valve. Frequently the pressure in the element has. dropped toa value lower than that of thereturn line. Upon subsequent opening of the trap, the greater pressure in the return line prevents free: draining of. the condensate. drainsfrom the trap, air must-flow in from the return line, resulting in disturbing .noise.

A specific object of my invention, therefore, relates to a provisionior collecting and cooling the condensate below the heating. element to. prevent floodingsof. the latter.

Still another object has totdo .with a provision for equalizing: the. pressure between the exhaust header and. the return line to permit free draining. of the condensate. A further object relates to a provision for preventing escape of steam through the pressure equalizing means when the exhaust header is at ashigher pressure than the return: line;

A further. object relates to the provision of a novel and simplified check valve-which is more economical. to manufacture but is more efilcient and less'subje'ct' to operating diificulties due to rust, scale and other im-puritiesthan those of the: prior art.

The

As the water 1 Another ohject relates to the provision of an improved heating element comprising heating tubes within which the distributing tubesare offset upwardly irom .the axesof the outer tubes to provide additional space for condensate.

Still another .objectrelates to the provision :of a condensatetr'ap havinga provision for equalizing' the pressure above .and below the valve to facilitate draining, the equalizing means being builtinto the .trapx itself.

These andother objects and advantages of my invention will be apparent to thoseskilled in the art after aconsidetation oftheiollowing description, reference ibeing had to the drawings ape pended hereto, which Figure l is a diagram of a steam heating sys-'- tem embodying .thepprinciples of my invention;

Figure 2 .isa diagram showing a modifiediorm of the invention;

Figured; isan enlarged .sectional view taken along an axial plane through the check-valve;

Figures isan enclview-of the check valve;

Figure 5 is a fractional sectional view of the cliecl: ,valvebut withatf-ixed orifice in place otthe checlt alve element;

Fi ure 6 is a, ndiagram .,showing still anot er modified form; and

Figure- 7 .is' an enlarged. sectional :view 7 of a. condensate trap embodying the principles of the present-- -invention.

Throughout the; drawings and in-the= -iollowi=n description, ,lilte numerals refer to like parts.

Referring now to the drawings and morepar ticularly :to Figure 1,, the-heating element is sup-e pliedqw-ith steam under any suitable pressure by neangofa steamsupply line {0 extending .from aconve tionalsteamgenerator (notshown)- control valve 1 [.of any suitahleedesign is con-,- nected to the supply line tor throttling the steam f ewmst the nn v h ad and s-p ded it -a handle ii -t r o veni e n lctjustment, al.thoughyan -y suitable automatic con-e i q evis m b nslaved to re ula this valve.

Th u pl es er li mbin wi h ans-X- h ust h de it n. n a t as n .W e suppl sii i Wi h n or partially enr- FQQHG Q by: Xh tlt flQ n m e 9 s e m d tributin tube 1 p o e i emth suppl heade .andcqmmu is rew h The outer nds it are lo e -an th ubes are. providedwith; axially spaced openings tlthreugh which the. steam. let-distributed to the. outer. tubes 21! which: enclose-the:distributingttubes ii The outer tubesi 21toil the heating. element communiw cate at their inner ends with the exhaust header I4 and their outer ends are closed by plugs 2I. Heat dissipating fins 22 are mounted on the outer tubes 20 to provide a large heat transfer surface over which the air for ventilation is circulated in a manner well known to those skilled in the art. The tubes 20 are disposed on a slight incline with their outer ends higher than their inner ends to drain the condensate into the exhaust header I4, and the axes of the distributing tubes I5 are spaced above the axes of the associated outer tubes to increase the space for condensate in the bottom of the tubes 2|].

A condensate duct 25 communicates with the bottom of the exhaust header I4 and extends downwardly therefrom for draining the header I4 and tubes to prevent flooding with condensate. The condensate tube has a portion 25 extending nearly horizontally but inclined slightly downwardly toward a condensate trap 21, preferably, but not necessarily, of the thermostatic type. The thermostatically operated trap includes a valve member 28 suspended inside a casing by a bellows 29 which is carried on a support 3| from the top of the easing 38 and is filled with a suitable expansible medium as is well known to those skilled in the art. The valve member 28 is shifted by expansion and contraction of the bellows 29 into and out of closed relation with an orifice 32 in the bottom of the casing 30.

The condensate duct 26 communicates with the interior of the casing 30 for delivering the condensate thereto. The orifice 32 discharges the condensate into a return line 33 which returns the condensate to the steam generator. An exhaust pump (not shown) may be provided to maintain a subatmospheric pressure in the line 33 as is well known to those skilled in the art. The duct 26 is provided with suitable fins 34, over which ventilating air is blown, thereby cooling the condensate. The trap orifice 32 is disposed at a lower elevation than the heating tubes 20 to maintain a head of condensate above the orifice to facilitate draining when the valve 23 opens.

- The upper end of the exhaust header I4 is connected with the return line, by-passing the valve orifice 32 of the trap, by means of a pressure equalizing duct 40, which communicates with .the header I4 through a control device 4I having a tapered threaded end portion 41 which screws into a pipe elbow 42. While the equalizing duct 4 is preferably connected to the top of the exhaust header l4, it is feasible to make the connection with the condensate duct 25, 26, at any point between the trap 21 and header I4, the essential consideration being the bypassing of the valve orifice 32. The other end of the equalizing duct is connected to the return line 33 through a T 39 which is also coupled to the trap beneath the valve orifice 32.

Referring to Figures 3 and 4, the control device in the preferred embodiment of my invention comprises a metal block or body 43, preferably of bronze, having an axially extending aperture 44 therein. One end of the aperture 44 is threaded at 45 to receive the cooperatively threaded end of the equalizing duct 40. A restriction 4B is provided within the aperture 44 to restrain rust, scale or other impurities from passing from the duct 40 through the aperture 44. The other end of the. aperture 44 has a sharp annular peripheral edge forming a seat for a valve disk 5I of suitable corrosion resistant metal, such as Monel metal. The disk 5| is retained in front of the opening by a plurality (four) of pins 52 disposed in axially extending, peripherally spaced recesses 53 in the end of the body 43 and preferably soldered therein, although they could be threaded into the recesses 53. The pins 52 serve as bearing supports for the edge of the disk 5| and are provided with heads 54 which overlap the edge of the disk to retain the latter in position over the end of the opening 44. The edge of the seat 50 is spaced axially inwardly from the end of the body 43 to provide for a limited amount of axial movement of the loose disk 5I toward and away from the seat 55.

Pressure on the outer side of the disk 5| forces the latter against the seat 5!] and thus closes the valve while pressure applied to the inner side of the disk urges the latter away from the seat 50 intoengag'ement with the overlapping heads 54, permitting flow of fluid out of the aperture 44 around the edge of the disk 5 I.

The operation of the embodiment of Figure l is explained as follows:

When the main valve II is opened, steam from the supply line I0 flows through the header I2 into the inner tubes I5 and is distributed from the openings Il into the outer tubes 20. Heat is transferred from the steam to the air through the fins 22 and the condensed steam run inwardly through the tubes 20 to the exhaust header. The water runs down through the condensate duct 25 and is further cooled by air passing over the fins 34 on the cooling duct 26.

Assuming a surplus of steam being delivered to the element, a certain amount of steam flows into the trap casing 33 with the condensate, thereby heating the bellows 2:: and causing the latter to expand. This forces the valve member 28 to be moved downwardly into closing relation with the orifice 32, preventing further escape of condensate. The condensate collects in the cooling duct 25 beneath the heating element as the steam in the latter condenses, until the condensate is sufiiciently cooled to contract the bellows 25, thereby withdrawingfthe valve member 28fro'm the orifice'32 and draining the casing 33 and duct 25, whereupon steam enters the casing once more, closing the trap valve as before.

Inasmuch as a presure differential is maintained in the heating element and exhaust header relative to the return line, the check valve disk 5! is held against the valve seat 53 thus preventing steam from escaping through the equalizing line 4?} to the return line 33.

When a lower rate of heating is desired, the control valve II is partially closed, throttling the steam flowing'into the heating unit. Condensation of the steam in the tubes 25 lowers the pressure therein. When the pressure in the exhaust header 1:; tends to drop below that in the return line 33, air from the return line flows through the equalizing line 40 and the check valve 4! into the exhaust header, where it mixes with the steam and displaces the condensate which is drained from the trap. This action is noiseless, for it eliminates the necessity for air to flow into the trap through the orifice 32. The heating element is uniformly heated, since there is no flooding of the tubes with condensate, and experience has proved that there is no water hammer noise at any time.

Instead of connecting the pressure equalizing from the latter flows upwardly through the bypass duct 9! through the control device past the disk i into the upper portion of the trap chamber 82, from which it can bubble up through the head of condensate in the duct 26 into the header l4. Equalizing the pressures in the trap chamoer 82 and discharge duct 85 in this manner permits free flow of condensate downwardly through the orifice 84 when the valve is opened.

The check valve disk 5! can be replaced by an apertured disk 56 in this embodiment as in the embodiment of Figure l, and the control device Al can be replaced by a thermostatic valve for controlling the by-pass duct as in Figure 2.

I do not intend my invention to be limited to the particular details shown and described herein, except as limited by the claims which follow. Although I have described my invention as embodied in a steam heating system, it is understood that the principles may be employed in other vapor heat transfer systems, as will now be apparent to those skilled in the art.

I claim:

1. In steam heating apparatus comprising a steam supply header, a heating element connected thereto, an exhaust header communicating with said element and a condensate return line, the improvement which comprises a condensate trap disposed at a lower elevation than said heating element and connected to said return line, a condensate cooling duct below said exhaust header interconnecting said trap and said exhaust header, and a pressure equalizing line connecting said exhaust header directly with said return line, said equalizing line including valve mean arranged and constructed to prevent steam from flowing from said exhaust header to said return line but permitting air to flow from said return line into said exhaust header.

2. In steam heating apparatus comprising a heating element, supply and exhaust headers connected thereto, a condensate trap connected to receive condensate from said exhaust header and .a return line connected to said trap to receive the condensate discharged therefrom, the improvement which comprises means including a pressure equalizing duct connecting said exhaust header with said return line independent of said trap, and valve means in said duct arranged and constructed to permit to flow from said re turn line to said exhaustheader but restricting flow of steam in the reverse direction. 3. In steam heating apparatus comprising a heating element, supply and exhaust headers con- 1 header with said return line by-passing said trap, and valve means in said duct arranged and con- ;structed to permit steam from flowing therethrcugh to said return line when said throttling valve 'is substantially open to maintain steam pressure in said header but permitting air to flow into said exhaust header from said return line when said throttling valve is partially closed and the pressure in said exhaust header tends to drop below the pressure in said return line.

4, The combination set. forth .in. claim- 3, in-

8 cluding" the further provision that said valve means in said duct is a check valve including an orifice and a gate movable into closed position over said orifice by steam pressure on one side of the gate, said gate being movable away from said orifice by air pressure on the other side of said gate. v 5. The combination set forth in claim 3, including the further provision that said valve means in aid duct is a thermostatic type valve including means responsive to flow of steam through said duct for closing said valve. v

6. In steam heating apparatus comprising a heating element, supply and exhaust headers con-- nected thereto, a steam supply duct connected with said supplyheader and having a throttle valve therein for throttling the steam supplied to said header, a condensate trap connected to receive condensate from said exhaust header and a return line connected to said trap to receive the condensate discharged therefrom, the improvement which comprises an air intake duct connected with said exhaust header, and valve means in said duct so arranged and constructed as 'to prevent steam from flowing therethrough when said throttling valve is substantially open to maintain steam pressure in said supply header but permitting air to flow into said exhaust header when said throttling valve is partially closed and the pressure in said exhaust header tends to drop below atmospheric pressure.

'2. In steam heating apparatus comprising a heating element, supply and exhaust headers connected thereto, a steam supply duct connected said return line, a pressure equalizing duct connecting said exhaust header with said return line independent of said trap, and valve means in said duct so arranged and constructed'as to autoits axis spaced above the axis of said heating tube to provide an enlarged space in said heating tube below said distributing tube for passage of condensate.

9. In heat transfer apparatus, a supply header, an exhaust header, a heating tube communicating with said exhaust header, a distributing tube communicating with said supply header and extending into said heating tube, said distributing tube being provided with axialy spaced discharge apertures and positioned in said heating tube with the axis of the distributing tube spaced above the axis of said heating tube'to provide an enlarged space below said distributing tube for passage of condensate through said heating tube into said exhaust header.

10. In heat transfer apparatus comprising a heating element, supply and exhaust headers connected thereto, a condensate trap casing includ ing a trap chamber having a connection with said exhaust header to receive condensate therefrom and a return line connected to said trap casing to receive the condensate discharged therefrom, the improvement which comprises an air intake duct communicating with said connection between said chamber and said exhaust header, and check valve means associated with said air intake duct for restricting the flow therein away from said chamber while permitting fiow toward said chamber.

11. The combination set forth in claim 10, including the further provision that said air intake duct is connected to said return line, thus by-passing said trap chamber.

1 In heat transfer apparatus comprising a heating element, supply and exhaust headers connected thereto, a condensate trap connected with said exhaust header to receive condensate therefrom, and a return line connected to the bottom of said trap to receive the condensate discharged therefrom, said trap comprising a chamber for receiving and collecting condensate and a valve in the bottom of said chamber for controlling the flow of condensate into said return line, the improvement which comprises a by-pass duct connecting the upper portion of said chamber with said return line, by-passing said valve, and means disposed in said by-pass duct for restraining flow of fluid therethrough toward said return line.

13. The combination set forth in claim- 12, including the further provision that said restraining means comprises a check valve preventing flow of steam or condensate from said chamber toward said return line but permitting a pressureequalizing flow of air from the return line into said chamber.

14. In a condensate trap comprising a chamber for receiving and collecting condensate having an intake opening in the upper portion and a discharge duct communicating with the bottom of said chamber, and a valve in said discharge duct for controlling the flow of condensate through said discharge duct, the improvement which comprise a by-pass duct communicating between said chamber above said valve and said discharge duct below said valve, and means disposed in said by-pass duct for restraining flow of fluid therethrough out of said chamber.

15. The combination set forth in claim 14, including the further provision that said restraining means comprises a check valve preventing flow of steam or condensate from said chamber toward said discharge duct but permitting a pressure-equalizing flow of air from the discharge duct into said chamber.

ARTHUR F. HUBBARD.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Certificate of Correction Patent No. 2,532,550 December 5, 1950 ARTHUR F. HUBBARD It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows:

Column 7, line 67 for the word permit read prevent;

and that the said Letters Patent should be reed as corrected above, so that the same may conform to the record of the case in the Patent Oifice. Signed and sealed this 6th day of February, A. D. 1951.

THOMAS F. MURPHY,

Assistant Commissioner of Patents. 

